A confocal setup to measure transmembrane potential in cardiac tissue with very high spatial and temporal resolution

We used a fast, fluorescent, potential sensitive indicator (di-4-ANEPPS) in combination with a specially designed setup which consists of an fluorescence microscope, a frequency doubled Nd:YAG laser and a 256 photodiode array system. The setup is especially designed to investigate tissue preparations in the mm range. The common setup can be reconstructed easily to a confocal laser microscope. This allows confocal microscopic detection of transmembrane potential with high temporal and spatial resolution. The axial resolution of the confocal results in a FWHM better then 15 /spl mu/m. Signals from papillary muscle were compared to images recorded by a CLSM (Leica TCS NT).